9-2
Name of
peripheral
equipment
Function and application
Main peri
pheral
equi
pment
Magnetic
contactor (MC)
An MC can be used at both the power input (primary) and output (secondary)
sides of the inverter. At each side, the MC works as described below. When
inserted in the output circuit of the inverter, an MC can also switch the motor
drive power supply between the inverter output and commercial power lines.
At the power supply (primary) side
Insert an MC in the power supply side of the inverter in order to:
1) Forcibly cut off the inverter from the power supply (generally,
commercial/factory power lines) with the protection function built into the
inverter, or with the terminal signal line.
2) Stop the inverter operation in an emergency when the inverter cannot
interpret the stop command due to internal/external circuit failures.
3) Cut off the inverter from the power supply when the MCCB inserted in the
power supply side cannot cut it off for maintenance or inspection purpose.
If you are to use the MC for this purpose only, it is recommended that you
use an MC capable of turning the MC ON/OFF manually.
Note:
When your system requires the motor(s) driven by the inverter to be
started/stopped with the MC, the frequency of the starting/stopping operation
should be once or less per hour. The more frequent the operation, the shorter
operation life of the MC and capacitor/s used in the DC link bus due to thermal
fatigue caused by the frequent charging of the current flow. If this is not
necessary, start/stop the motor with the terminal commands
FWD
/
REV
or with
the keypad.
At the output (secondary) side
Prevent externally turned-around current from being applied to the inverter
power output terminals (U, V, and W) unexpectedly. An MC should be used, for
example, if a circuit that switches the motor driving source between the inverter
output and commercial/factory power lines is connected to the inverter.
Note:
As application of high voltage external current to the inverter's output
side may break the IGBTs, MCs should be used in the power control system
circuits to switch the motor drive power supply to the commercial/factory power
lines after the motor has come to a complete stop. Also ensure that voltage is
never mistakenly applied to the inverter output terminals due to unexpected
timer operation, or similar.
Driving the motor using commercial power lines
MCs can also be used to switch the power supply of the motor driven by the
inverter to a commercial power supply.
Summary of Contents for FRENIC-Multi series
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